Butylene glycol is a humectant—a type of ingredient that draws water into the skin and helps it stay hydrated. It's a small, lightweight molecule commonly used in moisturizers to improve hydration without leaving a heavy feel on the skin.
Benefits
Increases skin hydration and moisture retention
Lightweight and absorbs quickly
Helps other active ingredients penetrate the skin more effectively
Science: Research demonstrates that butylene glycol, when combined with other humectants (like glycerin and hyaluronic acid) and occlusive ingredients in moisturizers, significantly improves skin hydration in both healthy skin and compromised skin conditions such as atopic dermatitis. It is recognized as a safe, effective humectant in dermatological formulations.
Glycerin is a naturally derived humectant—a ingredient that draws moisture from the air into your skin. It's one of the most widely used and well-studied moisturizing agents in skincare, helping skin feel softer and more hydrated.
Benefits
Attracts and retains moisture in the skin
Improves skin hydration and softness
Helps strengthen skin barrier function
Suitable for most skin types, including sensitive skin
Science: The Cosmetic Ingredient Review Expert Panel concluded glycerin is safe as used in cosmetics across all concentrations. Research shows glycerin effectively improves skin hydration and is well-tolerated with minimal irritation risk. It is also referenced in clinical guidelines for managing inflammatory skin conditions and maintaining skin integrity.
Hexylene glycol is a lightweight humectant and preservative booster used in skincare products to help retain moisture and improve product stability. It also enhances the penetration of other active ingredients into the skin.
Benefits
Helps skin retain moisture
Improves product texture and spreadability
Enhances effectiveness of preservative systems
Potential concerns
May cause mild irritation or redness in sensitive individuals (occurs in roughly 3% of eczema-prone skin)
Potential for delayed allergic contact reactions in susceptible people, though this is uncommon
Less irritating than propylene glycol under occlusion, but still worth avoiding if you have known sensitivities to glycols
Science: A 1989 study found hexylene glycol caused visible skin reactions in 2.8% of eczema patients at high concentrations (30-50%), with potential for delayed allergic sensitization in rare cases. It was less irritating than propylene glycol. One case report mentions hexylene glycol as a potential allergen in medical formulations, though reactions are uncommon at typical cosmetic concentrations.
Citric acid is a naturally occurring organic acid commonly used in skincare products as an exfoliant and pH balancer. It belongs to a group of ingredients called alpha-hydroxy acids (AHAs) that help remove dead skin cells from the surface.
Benefits
Gentle exfoliation to improve skin texture and appearance
Helps reduce the appearance of keratosis and acne
Balances product pH to maintain skin compatibility
Potential concerns
Can cause irritation, redness, or sensitivity in some users, especially with prolonged or frequent use
May increase sun sensitivity — sunscreen use is recommended when using AHA products
Not suitable for very sensitive or compromised skin without caution
Science: Citric acid is an established AHA used in cosmetics for superficial peeling and skin appearance improvement, though research emphasizes that caution should be exercised due to potential adverse reactions. It is widely produced industrially and well-established in skincare formulations.
Sodium benzoate is a preservative used in skincare products to prevent bacterial and fungal growth, extending shelf life. It's a salt derived from benzoic acid and is one of the most widely used preservatives in cosmetics, skincare, and food products.
Benefits
Prevents microbial contamination and extends product shelf life
Generally effective at low concentrations (0.1-0.5%)
Approved for cosmetic use by major regulatory bodies
Potential concerns
Can cause allergic contact dermatitis in sensitive individuals; identified as an allergen in medical hand cleansers
Recent research suggests long-term oral intake may affect bone health and increase osteoporosis risk, though topical skincare exposure is minimal
Science: Sodium benzoate is well-established as a safe preservative in cosmetics at typical use levels. However, emerging research indicates that chronic systemic intake may interfere with bone metabolism through the FGF2/p38/RUNX2 pathway. For topical skincare use, the exposure and absorption are minimal compared to dietary intake, but individuals with known sensitivities should avoid it.
Propanediol is a lightweight humectant—a molecule that draws water into the skin to keep it hydrated. It's also used in cosmetic formulations as a solvent and preservative booster, helping products stay stable and feel smooth on the skin.
Benefits
Hydrates and moisturizes the skin
Improves product texture and spreadability
Helps preserve formulations naturally
Science: Propanediol can be produced through bio-based fermentation (from glycerol using microorganisms), making it an environmentally friendly alternative to traditional chemical synthesis. It is widely recognized as safe in cosmetic and food applications, with established use as both a humectant and preservative enhancer.
Sodium chloride is common table salt, used in skincare products as a texture modifier, preservative, and to help balance formulations. In small amounts, it's generally well-tolerated by skin.
Benefits
Helps preserve product stability
Can enhance skin hydration when used in appropriate concentrations
Improves product texture and consistency
Potential concerns
High concentrations may irritate sensitive or compromised skin
Excessive topical salt exposure can potentially disrupt skin barrier function
May cause dryness or tightness in some individuals
Science: Sodium chloride is a naturally occurring electrolyte essential to skin physiology. Research indicates the skin actively regulates sodium levels through complex mechanisms involving the endothelium, immune cells, and lymphatics; however, peer-reviewed data specifically addressing topical sodium chloride in cosmetic formulations at typical use levels is limited.
Pentylene glycol is a lightweight humectant—a ingredient that draws water into the skin to improve hydration and texture. It's commonly used in serums, sunscreens, and moisturizers as a preservative booster and skin-conditioning agent.
Benefits
Improves skin hydration by attracting moisture
Lightweight feel, absorbs quickly without heaviness
Helps preserve product stability and extends shelf life
Potential concerns
Rare contact allergy reported in sensitive individuals
Emerging evidence suggests it may be an uncommon cosmetic allergen—if you have sensitive or reactive skin, patch test first
Science: Safety studies show a high margin of safety at standard use levels (87–671 in adults), with minimal skin penetration due to the ingredient's volatility. However, recent dermatological reports flag pentylene glycol as an emerging contact allergen in some individuals, warranting attention for those with sensitive skin.
Sodium Hydroxide is a strong alkaline chemical used in skincare products primarily as a pH buffer to neutralize acids and adjust the product's pH to safe levels for skin. It is not an active skincare ingredient and appears only in trace amounts in finished products.
Potential concerns
In concentrated form, sodium hydroxide is caustic and can cause severe chemical burns; however, in cosmetic products it is diluted and pH-buffered to safe levels
Undiluted or highly concentrated sodium hydroxide should never contact skin directly
Science: The provided research discusses sodium hydroxide only in a specialized medical context (10% solution for surgical cauterization of ingrown toenails), which is not relevant to cosmetic skincare use. In properly formulated skincare products, sodium hydroxide is used in minimal concentrations solely for pH adjustment and is considered safe by regulatory bodies including the FDA and EU.
Xanthan gum is a natural thickener derived from fermented bacteria that helps give skincare products a smooth, gel-like texture. It stabilizes formulas and prevents ingredients from separating, while also helping products spread evenly on skin.
Benefits
Creates smooth, pleasant texture
Stabilizes emulsions and prevents separation
Improves product spreadability and application
Science: Xanthan gum is an FDA-approved, anionic polysaccharide with a long history of safe use across food, pharmaceutical, and cosmetic industries since 1969. Its performance as a thickener and stabilizer is well-established in scientific literature, with no notable skin irritation concerns reported.
Orange peel oil is an essential oil extracted from the peel of sweet oranges. It's used in skincare for its pleasant citrus scent and potential antioxidant properties, though its skincare benefits are largely cosmetic rather than therapeutic.
Benefits
Antioxidant protection from vitamin C and limonene
Pleasant natural fragrance
May provide mild uplifting aromatherapy effect
Potential concerns
Can cause photosensitivity or increased sun sensitivity in some users
May irritate sensitive or compromised skin
Potential contact allergen, especially in those with citrus sensitivities
Science: Limited peer-reviewed data available specifically for orange peel oil in skincare formulations. General research suggests citrus essential oils contain antioxidant compounds, but concentration and stability in cosmetic products varies significantly.
Lavender oil is a fragrant essential oil extracted from lavender flowers, commonly used in skincare for its pleasant scent and traditional soothing properties. It's typically included in small amounts in formulations like serums, creams, and toners for both aromatherapy benefits and potential skin-calming effects.
Benefits
May help calm and soothe irritated skin
Provides pleasant fragrance
Traditionally used to promote relaxation
Potential concerns
Can cause allergic contact dermatitis or sensitization in some individuals
May trigger reactions in people with fragrance sensitivities
Essential oils can be irritating at high concentrations, though amounts in skincare are usually diluted
Science: Lavender oil has a long history of traditional use, but clinical evidence for skin benefits in cosmetic products is limited. Some research suggests lavender may have mild antimicrobial and anti-inflammatory properties, though studies on its effectiveness in skincare formulations are sparse.
Coco-Glucoside is a gentle, plant-derived cleanser made from coconut oil and glucose. It works by loosening and removing oil-based dirt and makeup from your skin without stripping away natural moisture.
Benefits
Effective at removing oils and makeup at lower concentrations than harsher cleansers
Gentle, non-ionic cleanser suitable for everyday use
Works well when combined with other cleansing ingredients to boost effectiveness
Potential concerns
Known contact allergen — can trigger allergic reactions in sensitive individuals and those with atopic skin
Higher prevalence in products marketed as 'hypoallergenic' or 'for sensitive skin' despite being a recognized irritant for some people
May cause allergic contact dermatitis, particularly in rinse-off products like cleansers and shampoos
Science: Recent research confirms coco-glucoside is an effective cleanser, particularly at removing oil-based soils, and performs best in low concentrations. However, it is classified as a known contact allergen and is surprisingly common in products marketed for sensitive skin, despite evidence that atopic and sensitive-skin individuals are most susceptible to glucoside-induced allergic reactions.
Caprylyl/Capryl Glucoside is a gentle, plant-derived cleanser and emulsifier made from coconut and glucose. It helps mix water and oil-based ingredients together and is commonly used in formulations to improve how active ingredients penetrate the skin.
Benefits
Mild surfactant that cleanses without harsh stripping
Helps deliver other skincare actives more effectively into the skin
Plant-derived and biodegradable
Compatible with sensitive skin formulations
Science: Research shows this ingredient functions effectively as an emulsifier in advanced delivery systems like microemulsions and lipid nanoparticles, enabling better skin penetration of active compounds. It has a strong safety profile with minimal irritation concerns and is widely accepted in cosmetic formulations.
Tetrasodium Glutamate Diacetate is a chelating agent that binds to metal ions (like calcium and iron) in skincare formulations, preventing them from causing unwanted chemical reactions or product degradation. It helps keep products stable and effective over time.
Benefits
Stabilizes skincare formulations by controlling metal ion activity
Helps prevent product discoloration and oxidation
Allows products to maintain consistency and efficacy during storage
Science: The Cosmetic Ingredient Review Expert Panel concluded in 2025 that Tetrasodium Glutamate Diacetate is safe for use in cosmetics at typical concentrations. Research shows it functions effectively as a chelator, with strong binding capacity for metals like calcium and iron.
Glyceryl Oleate is a natural emollient and emulsifier derived from glycerin and oleic acid (a fatty acid found in oils). It's used in skincare products to soften the skin, improve texture, and help blend water and oil-based ingredients together.
Benefits
Softens and conditions skin
Helps stabilize and blend product formulas
Well-tolerated by most skin types
Potential concerns
Undiluted form may cause minor skin irritation, particularly on damaged skin
Generally safe at cosmetic use levels (up to 12%), but concentrated versions should be diluted
Science: Safety assessment by the International Journal of Toxicology (2004) found glyceryl monoesters, including Glyceryl Oleate, to have minimal acute toxicity and low irritation potential at cosmetic concentrations. The ingredient is non-sensitizing and breaks down naturally in the body into fatty acids and glycerol.
Hydrogenated Palm Glycerides Citrate is a plant-derived emollient and texture modifier made from palm oil that has been chemically stabilized. It helps products feel smooth and creamy while improving how well oil and water-based ingredients blend together in skincare formulas.
Benefits
Improves product texture and spreadability
Provides light moisturizing properties
Helps stabilize product formulations
Science: Limited peer-reviewed data available for this ingredient. It is derived from palm oil derivatives commonly used in cosmetics and is generally recognized as safe by regulatory bodies when used as a cosmetic ingredient.
Sodium gluconate is a gentle humectant and chelating agent derived from glucose. In skincare, it helps retain moisture in the skin and can stabilize other active ingredients in formulations.
Benefits
Humectant properties that help skin retain moisture
Chelates metal ions that can degrade product stability
Mild and generally well-tolerated by most skin types
Science: Limited peer-reviewed data available specifically for sodium gluconate in skincare applications. The available research primarily focuses on its use in toothpaste formulations as a stabilizing agent, where it demonstrated good safety and compatibility with other active ingredients.
